Feminine of atsuwm; a bulwark, i.e. (figuratively) argument -- strong.
see HEBREW atsuwm
H6110. atsumah
[עֲצֻמָה] noun feminine defence; — plural suffix עֲצֻמוֺתֵיכֻם (so Baer Ginsb; van d. H. ׳עַצֻּמ) Isaiah 41:21 bring forward your defences, defensive arguments (CheHpt עַצְּבוֺתֵיכֻם your idols, after Gr, [so Lo Klo explain ׳עצמ, as mightiest aid, I. עצם]).
(ה)עצנו 2 Samuel 23:8, see I. עָדִין below I. עדן.